Ranjan Deka

Bio: Ranjan Deka is an academic researcher from Brown University. The author has contributed to research in topics: Population & Genetic isolate. The author has an hindex of 2, co-authored 4 publications receiving 24 citations.

Genetic variation of five blood group polymorphisms in ten populations of Assam, India

Abstract: Six Mongoloid and four Caucasoid populations of Assam, India, were examined for A1A2BO, Rhesus, Duffy and Diego blood groups. The distribution of their phenotypes and allele frequencies are presented. In the perspective of the ethnographic background, the results have been discussed in terms of genetic variability among these populations and probable reasons for its existence. The major groups, namely Caucasoids and Mongoloids, appear to form two separate groups in terms of these blood groups, though evidence is there to suggest intermixture.

Inter- and Intra-Island Genetic Diversity in Adriatic Populations of Croatia: Implications for Studying Complex Diseases in Isolated Populations

Abstract: Adriatic populations residing in over 7 islands of Croatia have been extensively studied for over the past 30 years. Linguistic, social, physical and biological anthropological data indicate that the island populations have a considerable degree of genetic isolation from each other. Within the islands as well, some degree of isolation exists between villages of several islands. To examine the effects of such genetic isolation on patterns of gene diversity at microsatellite loci, this investigation studied the coefficient of gene differentiation (GST) between villages within islands as well as between islands using allele frequency data at 9 short tandem repeat loci (D3S1358, vWA, FGA, THO1, TPOX, CSF1PO, D5S818, D13S317, and D7S820) in 31 villages of 4 islands (Hvar, Krk, Brac, and Korcula). Overall, none of the villages exhibits any significant departure from Hardy-Weinberg expectations of genotype frequencies at these loci. Decomposition of heterozygosity (H) as well as allele size variance (V) indicated significant inter-island gene differentiation (GST based on H = 0.0032, P < 10-4 ; GST based on V = 0.0036, P = 0.007), while the between villages within island component of genetic variation remain non-significant (GST(H) = 0.0029, P = 0.073 ; GST(V) = 0.0018, P = 0.315). The coefficient of coancestry (q) for the sampled unrelated individuals vary from village to village, ranging from 0.0 to 0.022, with an average of 0.0098. Comparison of estimates of inbreeding coefficient (F) based on genealogical data from these villages indicates that while q and F values are moderately correlated across villages, q is comparatively smaller (nearly one-half) than F. In other words, the high mutation rate at these STR loci diluted the effect of small effective size in producing correlation of alleles within individuals. The non-significant gene differentiation between villages within the islands is an advantage for disease-gene association studies using microsatellite loci, since data from several villages within each island may be pooled to enlarge the sample size without introducing complications of population substructure effects on the association results. (Researh supported by NIH grants GM 41399, GM 52601, and GM 58545).

Prevalence of metabolic syndrome in an island population of the eastern Adriatic coast of Croatia

Abstract: Metabolic syndrome (MS), an assemblage of risk factors (obesity, dyslipidemia, carbohydrate intolerance, hypertension) associated with development of cardiovascular diseases and type 2 diabetes, has assumed epidemic proportions in western societies. However, data on its prevalence in worldwide populations, particularly in non-industrialized societies is sparse. We report the prevalence of MS in an island population of the eastern Adriatic coast of Croatia, a distinctly homogenous population living in relative isolation with a traditional way of life style pattern. The participants consist of 381 unrelated individuals (136 males, 245 females), age 19 and above from the island of Hvar, one of the most populated Croatian islands with a population of over 11, 500 individuals. MS was assessed using the National Cholesterol Education Program criteria, with the exception of using body-mass index (BMI) and/or waist-hip ratio (WHR) as the predictors of obesity. Age-adjusted prevalence of MS was 26% (32% in males and 24% in females) with BMI and 42% (57% in males and 36% in females) with WHR as the measures of obesity. Pairwise correlations of age and sex-adjusted individual components, with the exception of fasting plasma glucose, are significantly associated with each other suggesting their co-morbidity. Prevalence of MS is substantially high in population of Hvar, comparable only to the Mexican American and the Native American populations. Our dana also illustrates that prevalence and associated risks of MS are dependent on the definition used for describing the syndrome.

Compositions and methods for identifying genetic predisposition to obesity and for enhancing adipogenesis

Abstract: The present invention provides compositions and methods for identifying a subject as having a genetic predisposition to obesity or at risk of developing obesity The present invention also provides compositions and methods for expressing a CREBRF polypeptide of the invention in a cell or precursor thereof and cells expressing a nucleic acid molecule encoding a CREBRF polypeptide of the invention

People of India: Biological diversity and affinities

Abstract: The Indian subcontinent comprises a vast collection of peoples with different morphological, genetic, cultural, and linguistic characteristics. While much of this variability is indigenous, a considerable fraction of it has been introduced through large-scale immigrations into India in historical times. From an evolutionary standpoint, it is of immense interest to quantify biological diversity in contemporary human populations, to study biological affinities and to relate observed patterns of affinities with cultural, linguistic and demographic histories of populations. Such efforts are intended to shed light on the peopling of India. The purpose of this paper is to present a broad overview of the physical (anthropometric) and genetic diversities and affinities of the peoples of India. I shall also attempt to examine how well biological, particularly genetic, diversities and affinities correlate with geographical, socio-cultural, and linguistic diversities and affinities. © 1998 Wiley-Liss, Inc.

Inbreeding and the Genetic Complexity of Human Hypertension

Abstract: Considerable uncertainty exists regarding the genetic architecture underlying common late-onset human diseases. In particular, the contribution of deleterious recessive alleles has been predicted to be greater for late-onset than for early-onset traits. We have investigated the contribution of recessive alleles to human hypertension by examining the effects of inbreeding on blood pressure (BP) as a quantitative trait in 2760 adult individuals from 25 villages within Croatian island isolates. We found a strong linear relationship between the inbreeding coefficient (F) and both systolic and diastolic BP, indicating that recessive or partially recessive quantitative trait locus (QTL) alleles account for 10-15% of the total variation in BP in this population. An increase in F of 0.01 corresponded to an increase of approximately 3 mm Hg in systolic and 2 mm Hg in diastolic BP. Regression of F on BP indicated that at least several hundred (300-600) recessive QTL contribute to BP variability. A model of the distribution of locus effects suggests that the 8-16 QTL of largest effect together account for a maximum of 25% of the dominance variation, while the remaining 75% of the variation is mediated by QTL of very small effect, unlikely to be detectable using current technologies and sample sizes. We infer that recent inbreeding accounts for 36% of all hypertension in this population. The global impact of inbreeding on hypertension may be substantial since, although inbreeding is declining in Western societies, an estimated 1 billion people globally show rates of consanguineous marriages >20%.

3000 years of solitude: extreme differentiation in the island isolates of Dalmatia, Croatia.

Abstract: Communities with increased shared ancestry represent invaluable tools for genetic studies of complex traits. "1001 Dalmatians" research program collects biomedical information for genetic epidemiological research from multiple small isolated populations ('metapopulation') in the islands of Dalmatia, Croatia. Random samples of 100 individuals from 10 small island settlements (n<2000 inhabitants) were collected in 2002 and 2003. These island communities were carefully chosen to represent a wide range of distinct and well-documented demographic histories. Here, we analysed their genetic make-up using 26 short tandem repeat (STR) markers, at least 5 cM apart. We found a very high level of differentiation between most of these island communities based on Wright's fixation indexes, even within the same island. The model-based clustering algorithm, implemented in STRUCTURE, defined six clusters with very distinct genetic signatures, four of which corresponded to single villages. The extent of background LD, assessed with eight linked markers on Xq13-21, paralleled the extent of differentiation and was also very high in most of the populations under study. For each population, demographic history was characterised and 12 "demographic history" variables were tentatively defined. Following stepwise regression, the demographic history variable that most significantly predicted the extent of LD was the proportion of locally born grandparents. Strong isolation and endogamy are likely to be the main forces maintaining this highly structured overall population.

Body mass index of adult males in 12 populations of northeast India.

Abstract: Background: Of the anthropometric indices, body mass index (BMI) is considered to be more nutritionally than genetically related. Thus, in a country with diverse ethnic groups like India, it is more appropriate to use BMI as an indicator of the nutritional status of adult population. However, literature on BMI of adult Indians is limited to certain geographical regions or populations, and little is known about the populations in the northeast region of the Indian sub-continent.Aim: The present report deals with the BMI of adult males in 12 populations of Northeast India with a view to understanding their nutritional status.Subjects and methods: Anthropometric data collected by the Anthropological Survey of India on 946 adult males aged 18-62 years of 12 populations in Northeast India were used in this analysis. The populations were broadly categorized into three groups, namely, caste, Hinduized and tribal groups. The data were collected mostly from rural areas, taking into consideration the different soci...

Genetic affinities of north and northeastern populations of India: inference from HLA‐based study

Abstract: India is like a microcosm of the world in terms of its diversity; religion, climate and ethnicity which leads to genetic variations in the populations. As a highly polymorphic marker, the human leukocyte antigen (HLA) system plays an important role in the genetic differentiation studies. To assess the genetic diversity of HLA class II loci, we studied a total of 1336 individuals from north India using DNA-based techniques. The study included four endogamous castes (Kayastha, Mathurs, Rastogies and Vaishyas), two inbreeding Muslim populations (Shias and Sunnis) from north India and three northeast Indian populations (Lachung, Mech and Rajbanshi). A total of 36 alleles were observed at DRB1 locus in both Hindu castes and Muslims from north, while 21 alleles were seen in northeast Indians. At the DQA1 locus, the number of alleles ranged from 11 to 17 in the studied populations. The total number of alleles at DQB1 was 19, 12 and 20 in the studied castes, Muslims and northeastern populations, respectively. The most frequent haplotypes observed in all the studied populations were DRB1*0701-DQA1*0201-DQB1*0201 and DRB1*1501-DQA1*0103-DQB1*0601. Upon comparing our results with other world populations, we observed the presence of Caucasoid element in north Indian population. However, differential admixturing among Sunnis and Shias with the other north Indians was evident. Northeastern populations showed genetic affinity with Mongoloids from southeast Asia. When genetic distances were calculated, we found the north Indians and northeastern populations to be markedly unrelated.